Lochinvar’s Knight XL commercial boiler is a modulating/condensing unit with 94.6% thermal efficiency, low NOx emissions and a fully modulating burner with 5:1 turndown. It is available in five models with 399,000, 500,000, 600,000, 700,000 and 800,000 Btu/hr. inputs. The units feature a compact design; small footprint; ASME stainless-steel heat exchanger; Smart System control with built-in cascading sequencer, outdoor reset, three pump control, night setback and password security; as well as a two-line, 16-character LCD display that uses words instead of codes to communicate.